Capacity on Demand (CoD) allows users to use as many hardware resources such as Central Processing Unit (CPU) as needed in information processing apparatuses such as server computers.
For example, to limit the number of CPUs in use with the CoD in an information processing apparatus having a plurality of CPUs, a user pays for the number of CPUs to be used at the time of purchasing the information processing apparatus. Thereby, the user's information processing apparatus allows as many CPUs as the user paid for to run, and prohibits the remaining CPUs from operating. Then, when the user wants to increase the processing capability of the information processing apparatus, the user purchases additional right-to-use licenses for CPUs, so that the CPUs that have been deactivated are activated immediately.
One of techniques relating to the CoD to deal with a failure in a licensed processor is to activate an unlicensed replacement processor and then deactivate the failure processor.
In addition, of recent multicore processors, there are processors whose cores each have a plurality of hardware threads. A hardware thread may be called a “strand”. The hardware threads in a core are capable of performing respective processes in parallel. Further, hardware resources such as registers may be specifically provided for each hardware thread.
Please see, for example, Japanese Laid-open Patent Publications Nos. 2004-288183 and 2004-318885, and International Publication Pamphlet No. WO 2007/099606.
By the way, in an information processing apparatus with a multicore processor including a plurality of cores each having a plurality of hardware threads as described above, the per-core licensing in the CoD has the following drawbacks. If an abnormality occurs in one of hardware resources that are specifically provided for each hardware thread and the abnormal hardware thread is replaced with another hardware thread, an excess of licenses may occur, depending on how the abnormal hardware thread is replaced.